The application contains a so-called left layer panel that's used mainly for mapping, for changes of the visibility or the order of layers in the project.  To open the left panel, tap on the button (1) on the map screen. 

Change layer visibility

To display or hide a layer, open the left layer panel and tap on the layer in the list. The highlighted layer (2) is shown in the map view.

Change layer order

The order in the layer panel defines the order of layers in the map view. To change the order, simply drag & drop the layer on the left edge of the panel (4).